Here's a roundup of information on some of the less well known, but likely or suspected environmental carcinogens, and what you can do to lower your exposure to them and reduce your chances of getting cancer.

Bisphenol A and plastic bottles

Bisphenol A (BPA) is a man-made chemical used in the manufacture of certain plastic products. It’s ubiquitous in the modern world, cropping up in everything from credit cards to car interiors to… baby bottles.

But if BPA enters the human body this otherwise useful chemical has hormonal activity similar to the female hormone oestrogen, and can disturb biological processes at very low concentrations. Considerable uncertainty remains as to whether exposure levels by the general public are harmful; nonetheless, several recent studies have linked it to harmful effects, especially that BPA may increase the risk for breast cancer.

How are you exposed to it?

If BPA-containing plastics are heated, the BPA can be released. For example, if you pour hot milk into a BPA-containing baby bottle, the BPA can enter the hot milk – and the baby who drinks it.

It’s been found that 55 times more BPA is released from bottles filled with hot water compared to those with cold water.

How to avoid it?

Dr Devra Davis, Professor of Preventive Medicine at Mt Sinai Medical Center in New York and author of The Secret History of the War on Cancer, recommends avoiding plastics stamped with the number 7 (contains BPA), as well as 3 and 6 (contains similar chemicals that may be cause for concern).

“It’s the very hard plastic ones you need to beware of – they will say ‘PC’ for ‘polycarbonate’,"says Dr Carl Albrecht, Head of Research at The Cancer Association of South Africa (CANSA).

"The softer plastic ones, like those for bottled water, have not been shown to be harmful. But rather don't reuse them a lot, taking them repeatedly in and out of the fridge. Still, the main potential danger with that is bacterial contamination.”

As a general rule, rather than getting too worried about whether a bottle contains BPA or not, Albrecht agrees that it’s best to simply avoid heating any plastic bottle. Use glass instead. You can also boil water or milk in another container and then allow it to cool before pouring it into a plastic bottle.

Plasticisers and clingwrap

Plasticisers are chemicals – known as DEHP and DEHA – used to make plastic softer and more ‘sticky’. They’re the reason why plastic wrap clings – and why it’s so hard to smooth it out again once you’ve scrunched it up. They’ve been found to cause cancer in animal studies.

How are you exposed to them?

Plasticisers can migrate into the food they’re wrapped around – especially fatty foods like cheese and meat. This process is accelerated at high temperatures such as when cling-wrapped food is microwaved.

How to avoid it?

After laboratory tests on various clingwrap brands, CANSA has given the nod of approval to Gladwrap, and in-house brands from Checkers, Pick ‘n Pay, Shoprite, SPAR and Woolworths – which are free of the offending chemicals.

You can also avoid using clingwrap by storing food in glass and plastic containers, or wrapping it in foil. Always remove clingwrap before warming food.

Trans fats

Trans fats, or trans fatty acids, are made (inadvertently) when plant oils are converted to margarine. In the 1990s, scientists realised that trans fats increased the risk of coronary artery disease. There is still no clear scientific consensus about whether trans fats cause cancer, but some studies have linked them with breast and prostate cancer.

How are you exposed to them?

You can ingest trans fats in many margarines and a lot of baked and fried goods.

How to avoid them?

Margarines made by Unilever are free from trans fats. Examples include Flora, Rama, Stork and the SPAR house brand. Woolworths foods also do not contain transfats. Get into the habit of reading food labels; many reputable brands advertise the fact that they are trans-fat free.

Acrylamide

Acrylamide is a chemical that forms spontaneously in carbohydrate food at high temperature, especially in potato crisps - and coffee.

At this stage acrylamide is considered to be a probable human carcinogen, associated with kidney cancer, and post-menopausal and endometrial cancer. It is also neurotoxic.

How to avoid it?

It may be premature to deny yourself the morning cuppa at this stage, but it’s never a bad idea to cut down (definitely to under five cups a day!) And we should all learn to live without the chips.

Dioxin

Dioxin refers to a group of toxic chlorinated organic compounds, produced as a by-product of many industrial processes, such as waste incineration and bleaching fibres.

Among the most toxic chemicals known, dioxins are long-lived in the environment and make their way into foods. They are soluble in fat, so they accumulate in the bodies of animals and humans over time. This means that small amounts are present in animal food products (meat and dairy). Thus, you can get dioxin in your body both by eating these foods and by inhaling emissions from pollutant sources.

Exposure has been linked to an array of negative health effects, including cancer, and reproductive and developmental problems.

How to avoid it?

Reduce intake of animal fat, and choose low fat dairy.

Don't burn waste, and avoid environments where incineration is being carried out.

Cell phone radiation

Davis feels strongly that the "safe rather than sorry" principle should also apply to cell phone use. Cell phones emit low doses of microwave radiation, which can penetrate the brain. Children's heads absorb cell phone signals more readily because they are smaller, have thinner skulls and contain more fluid. Several countries (France, Britain, Germany, Finland, Israel and Bangalore India) are getting much stricter on cell phone use for kids, but in others - the USA for one, cell phone companies are targetting children as young as five.

"We haven't been using cell phones very long," points out Davis. "Brain cancer can take 40 years to develop." Studies on cell phones have produced conflicting results, but, says Davis, many of those that found no significant risk for cancer did not follow research subjects for very long. Some studies suggest that the risk of developing brain tumours is doubled for people who've been using cell phones for 10 years or more.

How to avoid it?

Use cell phones with an earpiece and speakerphone so the phone is not held up against your head, and, says Davis, get into the habit of simply turning them off more often. She recommends that children under 12 should not use cell phones unless in emergencies. Don't use your cell when only a few bars show - this means the radiation will be greater in order to get the signal through.

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The information on Health24 is for educational purposes only, and is not intended as medical advice, diagnosis or treatment. If you are experiencing symptoms or need health advice, please consult a healthcare professional. See additional information.